This invention relates to alignment of optical components for testing and assembly of optical systems operating outside of the visible light range, and more particularly to the alignment of optical components for infra-red optical systems.
In the manufacture of optical systems, and more particularly fiber optic communications systems, it is essential to provide efficient optical coupling of optical components for testing, and optionally for assembly, purposes. By way of example, manufacture of certain optoelectronic devices for fiberoptic communications systems may require alignment along orthogonal X-Y-Z axes of a first optical element that has an aperture in the form of an opening or a window that is transparent with respect to light with a wavelength outside of the visible light range, e.g., a Fabry-Perot optical filter or a vertical cavity semiconductor laser, with a light beam emanating from a second optical element, e.g., a laser light source or an optical fiber serving as a light input source. More specifically, the two optical elements must be aligned in an X-Y plane and also precisely spaced along a Z axis that is normal to that plane. It is essential that the alignment process be precise, reliable, repeatable and fast.
The primary object of this invention is to provide an automated apparatus and method for precise three-dimensional optical alignment of optical components during assembly and inspection.
A more specific object is to provide an automated apparatus and method for three-dimensional optical alignment that employs a two-dimensional visible light machine vision system to assist active alignment of optical components based on the measured optical output at a wavelength of light outside of the visible range.
A further object is to provide an apparatus and method for aligning optical elements, one of which is a source of an optical beam with a wavelength outside of the visible range, with a 5 micron precision along the axis of the beam (Z axis) and a 0.25 micron precision in a plane perpendicular to the axis of the beam (the X-Y plane).
These objects are achieved by providing a motorized X-Y-Z motion apparatus having a movable support member for supporting a first optical element having an aperture for transmittal of light with a wave-length outside of the visible light spectrum and motion-translating means for selectively moving that support member along mutually orthogonal X, Y and Z axes, means for supporting a second optical element in the form of a source of a light beam having a wavelength outside of the visible range in a fixed position relative to the motorized motion apparatus with that light beam directed in the Z-axis direction at the aperture of the first optical element, a visible light vision system using visible light imaging for determining (a) the position of the first optical element relative to said visible light vision system in the X-Y plane and (b) the sharpness of the image of the first element as detected by the visible light vision system, an optical measurement device responsive to the beam for measuring a power-related value of the beam, and a motion control system for causing the motion-translating means to (a) move the movable support member in the X-axis, Y-axis and Z-axis directions as required to achieve X-axis and Y-axis alignment of said first optical element with said visible light vision system and maximize the sharpness of the image, and (b) subsequently move said movable support member first in the Z-axis direction and then in the X-axis and Y-axis directions as required to maximize a power-related value of said beam as measured by said optical measurement device. Other features and advantages of the invention are set forth in or rendered obvious by the following detailed description of the invention which is to be considered together with the accompanying drawing.